Insulator



C. F. SAUEREISEN.

INSULATOR.

APPLICATION mm) mm. :4. I920.

Patented Oct. 12, 1920.

FIG 3:

FIG. 2.

wa /25m UNITED STATES PATENT OFFICE.

CHRISTIAN F. SA'U'EREISEN, OF PITTSBURGH, PENNSYLVANI Patented Oct. 12, 1920.

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1 355 272 Specification of Letters Patent.

Application filed March 24, 1920. Serial No. 868,476.

To all whom it may concern:

Be it known that I, CHRISTIAN FQSAmm- EISEN, a citizen of the United States, and a resident of Pittsburgh, in the county of Alle gheny and State of ennsylvania, have made a new and useful Invention in Insulators, of which the following is a specification.

My invention relates to insulators and consists in a novel construction of the insulator surface which increases the efliciency of the insulator when used in connection with high tension currents andespecially when in use in high temperatures.

Most insulators have any exposed portion of their surface lazed to prevent the accumulation of V oreign material thereon which would tend to form a short circulating conductor. To provide a glazed surface, certain vitreous ingredients are used which differ from the ingredients of the bisque material of the remainder of the insulator. When heated to hi h temperatures, a surface of bisque materia becomes conductive of high tension currents but a glazed surface becomes conductive of the same current at far lower temperatures than an unglazed surface. This disadvantage of the glazed surface has been borne hitherto because of the greater objection to an exposed unglazed surface which retains dust, oil and other foreign matter adapted to form an undesirable conductor. 7

The main object ofmy invention is to retain the advantages of a glazed, dirt shedding surface and the unglazed-surface quality of being non-conducting at higher temperatures than will be withstood, non-conductively, by the glazed surfaces.

Extensive glazed surfaces do not readily expand and contract and are subject to crazing or cracking at high temperatures, while unglazed surfaces will endure the same temperatures without. so deteriorating because of their expensive qualities. Another object of my invention is to produce an insulator which is provide with glazed surfaces adapted to function in the usual manner but in which those partions subjected to the highest temperatures are unglazed to permit expansion and contraction.

To illustrate a preferred embodiment of my invention, I have shown it as applied to spark plugs. Figure 1 of the accompanying drawings is half view and half longitudinal section through a spark plug equipped with a porcelain insulator of my improved construction; Fig. 2 is an elevation of a modified insulating porcelain for a spark plug, and Fig. 3 is a view of a spark pin in which the insulator consists of mica an glass.

The spark plug shown in Fig. 1 includes a metallic shell 1 with cooperating clamp'portion 1, a' binding post 2 which is provided with an axially disposed electrode 3 terminating in a spark point 4 spaced from a cooperating spark point 5 mounted on shell 1. Spacing electrode 3 from shell 1 is a porcelain insulator 6. It will be understood that this spark plug functions by connecting post 3 to a current source and grounding shell 1 in the wall of an engine cylinder thereby completing a circuit which, when closed by suitable timing mechanism, will produce agas igniting spark at the gap between points 3 and 4.

Obviously any circuit between binding post 2 and shell 1 which does not include spark points 4 and 5 will render the plug inoperative. It will be noted that the surface of insulator 6 has a ring contact with the binding post at 7 and with the shell at 8. If a continuous layer or streak of dirt should extend along the insulator surface between these two rings, a circuit would be completed thereby with the results indicated above. To prevent this I glaze a band or zone 9 on insulator 6 adjacent post 2 but substantially spaced from shell portion 1 by a band or zone 10 of unglazed or bisque surface.

Foreign matter will slide or jar off of the vitreous zone 9 and a-short circuit between the binding post and shell is thus prevented. When the spark plug is operating in high temperatures, as produced in airplane enines for example, the ingredients which orm the polished or glazed surface become electrically conductive; hence if all the surface from the binding post to the shell were vitrified, the plug would be likely to short circuit at the high temperature although safe from such action at the lower temperatures. To prevent this happening I provide the unglazed zone 10.

Similarly: within shell 1 the lower part of insulator 6 has a zone 11 which is glazed and spaced from the lower part of electrode 3 and the insulator-contacting part of shell 1 by unglazed zones 12 and 13 respectively. The deposit of a continuous line of carbon between shell \1 and electrode 3 is prevented by the slick zone 11 and a conducting surface manufacturing methods.

provided with a continuous glazed surface and assembling same with the ignition system of an automobile and starting the plug sparking within a furnace. Upon successive tests the plug ceased sparking when the furnace tem eratures were between 900 and 1300 degrees ahrenheit. Thereafter :1 bisque surface was und around the porcelain which protrud e -l d from the shell and the plug again assembled as before. The temperatures then produced in the furnace before the plug ceased sparking ranged from 1700 to 1800 degrees Fahrenheit.

In Fig. 2 I show a modified insulator which would admit of more economical Either end could be dipped in parafiin and, after cooling, the plu could be dipped, parafiin end down, in a g sizing mixture, to the depth indicated, and then fired. In the insulatorshown in Fig. 1, bands 9 and 11 must be applied by brush or similar means which is a more expensive production operation.

In Fig. 3 I show a modified insulator which is in part built up of a plurality of mica sheets 14 cemented or clamped together and the edges of which form the unglazed surface correspondin in function to the bisque surface 10 in t e insulator shown in Fig. 1. Separating the built up sections of mica is a lass section 15 having a surface correspon mg in function to the glazed surface 9 in the insulator shown in 1 I am aware of the adaptability o my invention to insulators generally and do not wish to limit myself to its application to spark plug insulators. I realize the numerous arrangements of glazed and unglazed zones possible without departing from the spirit of my invention and I contemplate such modifications in its commercial development.

I claim 1. An insulating body provided with an exposed surface and adapted to insulate two electrodes which contact with said surface at spaced points; said surface including a glazed zone and an unglazed zone between said points.

2. An insulator provided with an exposed surface adapted to contact at spaced points with opposed electrodes and comprising altricity, a second conductor of electricity spaced therefrom, and an insulator between said conductors, the surface of said insulator, between said conductors, comprising glazed and unglazed areas.

4. In combination, a charged, electric conductor, an uncharged, electric conductor ad- 'acent same but spaced therefrom, and an insulator between said conductors; the surface of said insulator contacting with each of said conductors and that portion of said surface between said conductors including a complete band of glazed material separating said conductors and a complete band of unglazed material separating said conductors.

5. In a spark plug, a shell provided with a spark point, an electrode spaced from said shell by a vitreous insulator mounted on said shell and provided with a spark point adjacent said shell spark point, the surface of said insulator contacting with said shell and with said electrode and between said contacts being provided with an unbroken ring of glazed material and an unbroken ring of unglazed material. a

6. An insulating body having a continuous surface and adapted to insulate two electrodes at spaced points on said surface; said surface having a complete zone of glazed material, acting as a barrier to prevent adhesion of material forming a closed circuit between said electrodes, and a complete zone of unglazed material to prevent a closed circuit between said electrodes when said body is heated to a temperature suflicient to fuse said glazed material.

7. In a spark plug, a grounding element, a current supply element, terminals for each of said elements, and a orcelain insulator between said elements having a zone of glazed porcelain about its surface and a zone of unglazed porcelain about its surface; said zones be ng located between said elements.

8. In a spark plug, a threadedshell, a binding post, a terminal on said binding post extending through said shell and gpaced therefrom by an insulator; the surace of said insulator between said 0st and said shell comprising alternate ban s of glazed and unglazed materials.

In testimony whereof I have hereunto subscribed my name this 16th day of March. 1920.

CHRISTIAN F. SAUEREISEN.

Corrections in Letters Patent No. 1,355,272.

It is hereby certified that in Letters Patent No. 1,355,272, granted October 12,

1920, upon the application of Christian F. Sauereisen, of Pittsburgh, Pennsylvania,

for an improvement in Insulators, errors appear in the printed specification requiring correction asfollows: Page 1, 1ine 17, for the word circulating read c'ircuttirtg; same page, line 44, for the word expensive" read expansive; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 30th day of November, A. D., 1920.

[SEAL] L. B. MANN,

Acting Commissioner of Patents. 

